package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.SystemConstants;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisCommands;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.RedisCommand;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.util.*;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private CacheClient cacheClient;

    @Override
    public Result queryById(Long id) {
        //缓存穿透
        //Shop shop=queryWithPassThrough(id);
        Shop shop=cacheClient.queryWithPassThrough(CACHE_SHOP_KEY,id,Shop.class,this::getById,CACHE_SHOP_TTL,TimeUnit.MINUTES);


        //互斥锁解决缓存击穿
        //Shop shop=queryWithMutex(id);
        //Shop shop=cacheClient.queryWithLogicalExpire(CACHE_SHOP_KEY,id,Shop.class,this::getById,CACHE_SHOP_TTL,TimeUnit.MINUTES);

        if(shop==null){
            return Result.fail("店铺不存在");
        }
        //返回
        return Result.ok(shop);
    }

    public Shop queryWithMutex(Long id){
        String key=CACHE_SHOP_KEY+id;
        //1.从redis查询商铺缓存
        String shopJson=stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if(StrUtil.isNotBlank(shopJson)){
            //3.存在，直接返回
            Shop shop= JSONUtil.toBean(shopJson,Shop.class);
            return shop;
        }
        //判断命中的是否是空值
        if(shopJson!=null)
        {
            //返回一个空值
            return null;
        }
        //4.实现缓存重建
        //4.1获取互斥锁
        String lockKey="lock:shop:"+id;
        Shop shop= null;
        try {
            boolean isLock=tryLock(lockKey);
            //4.2判断是否获取成功
            if(!isLock){
                //4.3失败，则休眠并重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            //4.4成功，跟据id查询数据库
            shop = getById(id);
            //5.不存在，返回错误
            if(shop==null){
                //将空值写入redis
                stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
                return null;
            }
            //6.存在，写入redis
            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            //7.释放互斥锁
            unlock(lockKey);
        }
        //7.返回
        return shop;
    }

//    public Shop queryWithPassThrough(Long id){
//        String key=CACHE_SHOP_KEY+id;
//        //1.从redis查询商铺缓存
//        String shopJson=stringRedisTemplate.opsForValue().get(key);
//        //2.判断是否存在
//        if(StrUtil.isNotBlank(shopJson)){
//            //3.存在，直接返回
//            Shop shop= JSONUtil.toBean(shopJson,Shop.class);
//            return shop;
//        }
//        //判断命中的是否是空值
//        if(shopJson!=null)
//        {
//            //返回一个空值
//            return null;
//        }
//        //4.不存在。跟据id查询数据库
//        Shop shop=getById(id);
//        //5.不存在，返回错误
//        if(shop==null){
//            //将空值写入redis
//            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
//            return null;
//        }
//        //6.存在，写入redis
//        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
//        //7.返回
//        return shop;
//    }
//
    private boolean tryLock(String key){
        Boolean flag=stringRedisTemplate.opsForValue().setIfAbsent(key,"1",10,TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }
    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }

    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id=shop.getId();
        if(id==null){
            return Result.fail("店铺id不能为空");
        }
        //1.更新数据库
        updateById(shop);
        //2.删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY+id);
        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        //判断是否需要根据坐标查询
        if(x==null||y==null){
            // 根据类型分页查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }
        //计算分页参数
        int from=(current-1)*SystemConstants.DEFAULT_PAGE_SIZE;
        int end=current*SystemConstants.DEFAULT_PAGE_SIZE;

        //3.查询redis，按照距离排序，分页，结果：shopId，distance
        String key=SHOP_GEO_KEY+typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results=stringRedisTemplate.opsForGeo()
                .search(
                        key,
                        GeoReference.fromCoordinate(x,y),
                        new Distance(5000),
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
                );
        //解析出id
        if(results==null){
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list=results.getContent();
        if(list.size()<=from){
            return Result.ok(Collections.emptyList());
        }
        //4.1截取from-end部分
        List<Long> ids=new ArrayList<>(list.size());
        Map<String,Distance> distanceMap=new HashMap<>(list.size());
        list.stream().skip(from).forEach(result->{
            //4.2获取店铺id
            String shopIdStr=result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            //4.3获取距离
            Distance distance=result.getDistance();
            distanceMap.put(shopIdStr,distance);
        });
        //5.跟据id查询shop
        String idStr=StrUtil.join(",",ids);
        List<Shop> shops=query().in("id",ids).last("ORDER BY FIELD(id,"+idStr+")").list();
        for(Shop shop:shops){
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        //返回
        return Result.ok(shops);
    }
}
